Abstract

Property owners and developers need predictable costs and timelines to manage and transact properties. Obtaining regulatory closure on impacted sites typically means obtaining a “sign-off” document from provincial regulators. However, remediation costs can sometimes outweigh otherwise inherent property values and limit redevelopment options for significantly impacted sites. Risk assessment (RA) can be helpful in these instances in reducing costs by eliminating pathways of concern or establishing standards that are site-specific.

But what happens when a site contains LNAPL? Most jurisdictions allow RAs on PHC-impacted sites, but usually contain additional restrictions when LNAPL, or even just a sheen, is present. Regulators can require everything from assessments into LNAPL mobility to active remediation/removal to the “extent practicable”. This can often lead to expensive remediation programs and long-term monitoring that can cause cost overruns and scheduling delays to project objectives.

LNAPL presence is problematic even at the site characterization stage. It is notoriously difficult to directly detect in-situ, often requiring indirect and inferred means of assessment. Fortunately, there are direct-sensing tools to detect and characterize LNAPLs in-situ, thereby greatly facilitating their timely, accurate and detailed delineation.

Once confirmed to be present (assuming it does not otherwise pose a risk to human health or the environment) there are several new Risk Management Measures available to facilitate RA-based closures at LNAPL sites. Mobile plumes can be immobilized using novel forms of in-situ stabilization techniques. Bulk LNAPL can also be adsorbed and degraded using the latest generation of in-situ remedial amendments. These technologies are often faster-acting and less expensive than traditional LNAPL extraction (excavation and multi-phase extraction).

Details on each of these innovative technologies will be presented and discussed. Real-world case studies and cost considerations will also be presented. Overall, this presentation will illustrate new methods to facilitate RA-based closures, obtain regulatory approvals and allow the redevelopment of sites containing LNAPL in a more sustainable, timely and cost-effective manner.

Presenter: Kevin French, B.A.Sc., P.Eng.

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